Method of pasteurizing and deodorizing lacteal fluids under vacuum



3, 1937. H. L. MURRAY 2,089,132

METHOD OF PASTEURIZING AND DEODORIZING LACTEAL FLUIDS UNDER VACUUM Filed March 20, 1953 3 Sheets-Sheet l Aug.'3, 1937. MURRAY 2,089,132

METHOD OF PASTEURIZING AND DEODORIZING LAGTEAL FLUIDS UNDER VACUUM Filed March 20, 1953 -s sheets-sheet 2 Aug. 3, 1937.

H. L. MURRAY METHOD OF PASTEURIZING AND DEODORIZING LACTEAL FLUIDS UNDER VACUUM FilKed March 20; 1953 s Sheets-Sheet s 37 /ia Ji Patented Aug. 3, 1937 UNITED STATES METHOD OF PASTEURIZING AND DEODOR- IZING LACTEAL FLUIDS UNDER VACUUM Henry Lamont Murray, Epsom, Auckland, New

Zealand, asaignor to Murray Deodorisers Limited, Auckland, New Zealand, a company of New Zealand Application March 20, 1933, Serial No. 661,851 In New Zealand May 26, 1932 10 Claims.

The present invention has for its primary object a method of and apparatus for, the continuous pasteurization and deodorization of lacteal liquids or the like, such as cream, under vacuum.

It has previously been proposed to simultaneously pasteurize and deodorize cream under vacuum by a batch process, but same has not come into commercial use owing to a variety of technical objections, of which possibly the most relevant is the injurious effect of the process on the body of thecream.

It has been also primarily proposed to pasteurize cream, milk or the like by direct injection of steam at a comparatively high pressure or velocity, such proving satisfactory only in cases where the concussion effected has not been det rimental to the article. Thus it has been found practicable in the handling of whey, but not of cream.

It has been found by experience that where pasteurization in the usual manner under atmospheric conditions, is followed by deodorization, the additional concussion and treatment given to cream during deodorization results in many cases in a higher fat loss during churning, but by the present process of pasteurizing under vacuum it is found that under usual conditions the fat loss even when such pasteurization is followed by deodorization is usually less than that occasioned by pasteurization alone under present flash conditions.

Amongst the advantages attendant upon vacuum pasteurization, the following are the most pertinent:Reduction of churning losses and increased overrun; improved pasteurizing efliciency; avoidance of scorched, cooked or stewed flavours; minimum interference with vitamins; no necessity for dilution; reduction of power and steam consumption and automatic operation.

To enable the perfecting of a satisfactory continuous process for the pasteurization and deodorization of cream and other' lacteal liquids or the like under vacuum, it has been found necessary to devise entirely new processes or methods of pasteurizing together with apparatus therefor, such methods of pasteurizing and apparatus therefor being advantageous independently under atmospheric conditions, and accordingly, as pointed out in the claims hereunto appended, such processes of pasteurization and apparatus therefor are claimed independently of their use in a continuous process of pasteurization and deodorization.

It is to be understood, however, that it is not desired to limit the invention to the particular processes of pasteurization hereinafter disclosed as other forms of pasteurizers such as the flash pasteurizers at present in use, could be strengthened and adapted for vacuum pasteurization and 5 deodorization, but with very inferior results.

It is claimed, however, that the present invention is the first in the field to produce a continuous and satisfactory process or method of continuous pasteurization and deodorization under vacuum and accordingly the ambit of the invention is only to be limited in so far as is necessary to support the validity of the annexed claims.

According to the improved method of pasteurization, steam is gently passed in a diffused form into the cream or alternatively the cream is gently passed in a diffused or rain form through the steam.

Such methods of pasteurizing creamcomprise gently diffusing steam into a flowing substantially thin body of the fluid to be treated to cause a substantially instantaneous raising of the temperature of the liquid to that required for pasteurizing or alternatively splitting up the cream into small drops such as rain or diffused form, and allowing it to pass through a chamber within which there is steam at a temperature suited for pasteurization, so that the drops of cream are heated to a pasteurizing temperature.

By splitting up the cream into diffused form or drops, the steam can act upon it much more readily with the result that in the comparatively short passage from the entrance to the exit of the pasteurizing vessel, each drop is raised in temperature to that required for pasteurization.

Although the word drops has been used as being most suitable for clearly indicating that it is required to split up the cream so as to make it very readily accessible to the steam during its passage within the pasteurizing vessel, it is not desired to limit such splitting up of the cream to drop form only, as obviously a thin film or films of cream would be substantially equally accessible to the quick heating action of the steam. The thin body or drops will hereinafter be referred to simply as a stream.

To enable the chemical action of acid neutralization to be completed, it is desirable for the cream to be retarded on discharge from the pasteurizer if not used in conjunction with a deodorizer, in which event with the pasteurizer used as an atmospheric arrangement, to avoid creation of vacuum in the pasteurizing chamber by condensation of the steam (with consequent 55 hole in the seated hos 28, the arrangement being such that by rotating handwheel or like II, the spindle 21, central spindle 24 and rings 20 I0- tate, and at the same time the detachable joint and union nut means l8 permit of ready detachment of the various parts from the steam jacket 12 for cleaning purposes.

The steam inlet pipe 13A with valve l3 may pass tangentially into the steam jacket 12 to prevent direct impingement of the steam on to the rings 20.

Engaging within the spaces 2| between the rings 20 there are knife blades 32 (see Figure 3) all connected together'by lateral rod means 33 and bridge members 34, these latter being secured to the steam jacket 12 in such manner that by unscrewing the external nut means 35, the whole of the blades 32 can be withdrawn from engagement within the spaces 2 I, thus permitting the rings 20 to be'withdrawn laterally, when so desired for cleaning p'urposes.

Obviously, instead of the straight blades 32 as shown, said blades could be of circular form and permitted to rotate on a shaft which could be raised as desired in similar manner to that described.

A thermometer 36 is preferably fitted to the outlet 3. I

With the two forms of pasteurizer described as in Figures 1 and 2, pasteurization is effected by diifusing steam into the liquid, but in the pasteurizersof Figures 6 and '7, this process is reversed, the liquid being passed in diifused or rain form through the steam.

The apparatus of Figure 6 comprises a pasteurizing chamber 31 preferably cylindrical, in

horizontally and upwardly in goose neck or U form 41 to terminate in outlet 3.

A thermometer 38 is provided on the goose neck 41 the latter alsohaving a drain cock 48.

In the apparatus of Figure 7 which is a modifled form of that shown in Figured, the pasteurizing chamber 31 is of inverted conical form having the spray mechanism mounted to the top thereof. 4

The spray mechanism comprises a liquid chamber 49 with removable cover 50 and having inlet pipe 2 connected thereto, the spray plate 5| which has the orifices 43 therein in ring form (none in the centre) being seated in the bottom of the chamber 49 and having knob means 52 so that when cover 50 is removed, the spray plate 5| can be lifted out.-

The expansion chamber 38A surrounds the upper portion of the pasteurizing chamber 31, the steam gaining admission to the latter from the former by way of a perforated conical distributor 53 which rests on a bead 54 formed in chamber 31 and fits at its top around the bottom of liquid chamber 49.

Sides of the expansion chamber 38A converge outwardly to form an outer extension 55 into which the steam pipe I3A passes with preferably a bell mouthed outwardly faced end 56 within extension 55.

The pasteurizers as illustrated in Figures 1, 2, 6 and 7 may be used as independent units or in conjunction with deodorizing apparatus, but in any event, to complete pasteurization, it is preferable for the liquid after passing through the pasteurizer to be held in retarder means for a period sufflcient to complete pasteurization and form with top and bottom pipes 38 and 39 secured thereto in a manner, as by joints 40, permitting ready detachment of said chamber 31 from said pipes 38 and 39, thetop pipe 38 being gradually reduced in diameter from'say, eleven inches at the top of the chamber 31 to four inches at its upper part 4|, this latter preferably having a right angle bend to prevent excessive height.

The top pipe 38 forms an expansion chamber for steam admitted thereto from the steam pipe i3A with control valve 13, before said steam passes into the pasteurizing chamber 31, so that the steam meets the liquid at a pressure only slightly above atmospheric.

Secured to the top pipe or expansion chamber 38 just above the pasteurizing chamber 31, a hollow spray ring 42 is secured having small orifices 43 (say 720 holes in a nine inch ring with four inch centre hole) in its bottom face, this spray ring 42 being connected by inlet pipe 2 to a float tank 44 which may be of the type described in previous Letters Patent No. 1,641,349

the source of supply pipe 45 from which the the chemical action of the neutralizing agent.

Where the pasteurizers are used in conjunction with deodorizer means, a separate vessel for retardation purposes is not necessary as retardation can be effected in the deodorizer.

Considering first of all the use of the pasteurizers as independent units, with those of the type shown in Figures 1 and 2, the retarder vessel in a preferred form comprises a container 51 (see Figure 4) open to the atmosphere but substantially closed at its top by a cover plate 58 having a downwardly projecting cylindrical portion 59 concentric with the container 51, the

connection of the container 51 to atmosphere being byway of this cylindrical portion 59.

The container 51 has an outlet pipe 60 situated upwardly from the bottom of the container 51 and projecting to near the said bottom in bend form, a drain 6| also being provided to container 51.

The pasteurizer (as in Figures 1 or 2) is connected with its outlet 3 passing tangentially into the container 51 at the top thereof, the pasteurizer being mounted at a lower level than that at which the outlet 3 is connected to the container 51 to ensure sealing of the pasteurizer.

With the pastemizers of Figures 6 and 7, as the passing of the liquid through the steam would tend to create a vacuum within the pasteurizing chamber 31, when these pasteurizers are used as independent or atmospheric units, it would be necessary to fit a vacuum and pressure relief valve 62 (of known type) to a convenient point on pasteurizing chamber 31 (see Figure 8).

When so used, the goose neck 41 would be eliminated as the bottom of the bottom pipe 38 projecting into the liquid within the container '51 (Figure 8) would give the desired seal.

case would not require the cover plate 8 or portion II as in Figure 4 and a simple elevated outlet 60 from container I'l would be satisfactory.

Now considering the pasteurizers when used in conjunction with convenient deodorizing apparatus such as of the type described in Ser. No. 557,858 when pasteurizers of the type shown in Figures 1 or,2 are to be applied, a float tank 44 is coupled to the inlet 2 (see Figure 5) and the pasteurizer vertically connected to the steam scrubber pipe 63 of the deodorizer 64, this scrub ber pipe 63 passing as at present in a semi-circular bend across said deodorizer 64 and then horizontally and tangentially thereinto in fishtail form 65.

In view of the steam scrubbing of the liquid while within the pasteurizer, this semi-circular upper portion of the pipe 64 may be eliminated, the latter passing direct to the fishtail 65.

To efiect retardation of the liquid within the deodorizer 64 in manner similar to that applied when containers 5'! are used, the suction pipe 66, which is the liquid outlet pipe from the deodorizer separator chamber 61 is extended by pipe 68 upwardly within the latter (see Figure 5) said extended pipe 68 being concentrically surrounded by a cylindrical baflle ring 69 which at its top edge is above the top level of extended pipe 68 and is clear of the separator chamber bottom 61, vertical stays or ribs 10 supporting said baille ring 69 and at the same time acting as antiswirl bailies.

With the pasteurizers as in Figures 6 and 7, the connection to the deodorizer 64 simply comprises an upward pipe H (see Figure 9) connected to the goose neck pipe 41, passing horizontally and tangentially into the deodorizer 64 in enlarged fishtail form 65.

In Figure 9, the pasteurizer has, for the purpose of clearness of illustration, been shown as being away from the deodorizer 64, but in actual practice said pasteurizer would preferably be mounted to the side of the deodorizer with suitable brackets fitted thereto so as to form a compact unit.

Under certain circumstances, as it may be desirable to be able to independently vary the degree of vacuum in the pasteurizer and the deodorizer, as under usual conditions to obtain effective deodorization it may be necessary to have a much greater degree of vacuum in the deodorizer, than is permissible in the pasteurizer to obtain adequate and desired pasteurization, suitable means such for instance as the automatically actuated valve means as shown in Figures 9 and 10 are fitted to control the degree of vacuum applied to the pasteurizer.

These automatically actuated valve means comprise a large cylinder 12 (see Figure 10) with smaller cylinder 13 extending concentrically from one end thereof, there being a space H between large and small pistons 15 and 16 (which fit their respective cylinders 12 and 13) which is common to both cylinders, the pistons 15 and 16 being connected to a single piston rod 11.

The cylinders 12 and 13 are preferably vertically disposed (as shown) a cover 18 being provided to the top of the large cylinder 12 from which pipe I9 passes to a suitable point on the pasteurizer chamber 31, the space 14 having pipe connected thereto passing to a suitable position on the deodorizer 64, preferably the top of the ejector condenser ll at which point there would be the full degree of vacuum as applied to said deodorizer 84.

The bottom end of the small cylinder I3 is open, the piston rod l'l passing therethrough to a connecting rod 82 which is connected to a lever II which controls the opening and closing operations of preferably a butterfly type valve '4 located in the connecting pipe II or upperward portion of goose neck 41.

The connecting rod 82 may have a shoulder II to receive removable weights '8.

To the connecting rod I2 piston rod I1 or valve lever 83, dash pot means of known type (not shown) may be fitted for the purpose of preventing rapid movements of the valve l4 and the operating members connected thereto.

In operation, for the purpose of simplicity and clearness, it will be considered that the liquid to be pasteurized is cream, although it will be understood that there are liquids other than lacteal liquids which could be pasteurized, such as for instance, fats or oils.

Considering that there is a supply of cream to be treated by the pasteurizer of Figure l as an independent unit, said cream would fiow by gravity or pump means into the inlet 2 of the diiiuser tube i at a low pressure (say lb. to the square inch) and the steam pressure in the jacket I! would be controlled to be just sufiiciently in excess to pass gently through the orifices ll into the cream flowing along the annular space 9 between the diffuser tube I and the diverter I without allowing cream to how into the jacket i2.

This would cause the cream and steam to mix with resultant heating of the cream with a minimum of concussion and the cream and steam would pass along the diffuser tube to the branch fitting 5 and through outlet 3 into the retarder vessel or container 51 (see Figure 4).

Due to passing into the latter at the periphery thereof, the cream would (due to the velocity of fiow) spiral down within the vessel andbe held therein before discharge at the outlet 00 for a period sufi'icient to enable completion of chemical action of acid neutralization (one minute or so).

While the diifuser tube has cream or like passing througlnthe heat of the jacket i2 tends to cause a deposit of solids to form a skin on the diffuser tube which, if left, would have an insu-' lating effect and tend to choke the orifices II.

To prevent this, the handwheel II is occasionally turned so as to cause the diverter i to rotate with the result that the scraper blades ll would remove the deposit.

With the pasteurizer of Figure 2, the operation is the same as that just described except in that the steam gently enters the annular space 9 within which the cream is fiowing by way of the spaces 2i between the rings 20, and the solids which would deposit due to the heat of Jacket l2 and would tend to block the spaces 2!, being removed therefrom by the knife blades 32 engaged within said spaces 2i, cleaning being effected by rotation of handwheel l l which causes the rings 20 to rotate.

Now if either pasteurizer of Figures 1 or 2 is applied to a deodorizer 64 as in Figure 5, the operation and control is simplified because the cream and steam come under the influence of vacuum as soon as they pass into the pasteurizer, the cream via the inlet 2 of the pasteurizer from the float tank 44 and steam via diffuser orifices I! (Figure l) or ring slots 2| (Figure 2).

It will be assumed that it is necessary to pasteurize at F. This necessitates the use of 11 inches of vacuum in the pasteurizer and the vacuum to be maintained in the deodorizer will therefore be 11 inches plus that required to raise the weight of cream from the bottom of the pasteurizer into the deodorizer 64 via pipe 63.

Thus the cream raised to the desired pasteurizing temperature passes along with the excess steam in a frothy state through pipe 63 and fish tail 65 to the deodorizer and is thereby deodorized in known manner and then swirls to the bot tom of the separator chamber 61 to be held or retarded (if desired) by the baiile ring 69 and pipe extension 68 for a period sufflcient to effect completion of pasteurization before finally flowing down suction pipe 66.

The excess steam above referred to is that steam in excess of that required to raise the cream in the pasteurizer to pasteurizing temperature and which is necessary to enable satisfactory deodorization to be efiected in a deodorizer of the type employed in Serial No. 557,858.

As has already been indicated, it will usually be desirable to provide means for independently varying the degree of vacuum in the deodorizer and in the pasteurizer, apparatus for this purpose having already been described with reference to Figures 9 and 10 of the drawings.

In operation, (see Figures 9 and 10) the areas of the large and small pistons 15 and 16 are such that the high degree of vacuum applied by pipe 80 from the deodorizer 64 to the space 14 acting upon the bottom of large piston 15 and top of small piston 16 will substantially balance the desired lower degree of vacuum of the pasteurizer as applied to the top of large piston 15 by way of pipe I9.

As long as this balance is maintained, the piston rod 'l'l would remain stationary and the butterfly valve 84 open, but if the degree of vacuum in the pasteurizer should exceed the desired degree, this greater degree would aiiect the top of large piston 75 and cause same to move upwardly.

This would cause the valve lever 83 to move butterfly valve 84 to give a restriction of passage in the pipe II (or 63 of Figure 5) so that it will be obvious that in view of the pasteurizer obtaining its vacuum from the deodorizer 64 by way of this connecting pipe II, the vacuum within the pasteurizer would fall and the valve mechanism operate to govern the degree of vacuum of the pasteurizer to that lower degree desired.

Let it be assumed that the ratio between the two vacua as adjusted by the valve means is 2% to 1, if desired to increase the ratio, this is obtainable by the addition of one or more weights 86 to the connecting rod 82 which will cause a greater degree of vacuum in the pasteurizer to be required to balance the added weights 86.

It may be pointed out that the greater the dif ferencein the respective vacua the greater the temperature drop on issuance of the boiling cream from the butterfly valve 84 and therefore the greater the quantity of vapour formed at that point by utilization of latent heat thus reducing the quantity of excess steam necessary from the boiler for deodorization purposes.

Now considering the operation of the pasteurizers as shown in Figures 6 and '7 used in the first case as atmospheric and independent units (not under vacuum) in both cases the operation is substantially the same, the steam being admitted to the pasteurizing chamber 31 in a manner tending to allow it to expand and lose its superheat and thus fall to a temperature suited for pasteurization.

With such atmospheric use of the pasteurizer,

the cream while passing through the steam would cause condensation of the latter and the'creation of a degree of vacuum which would tend to hold up the cream within the chamber 31 if it were not for the provision of the vacuum and pressure relief valve 62 which would be set to relieve any vacuum created and would relieve any pressure above the low pressure desired.

The amount of steam admitted to the pasteurizing chamber is controlled to be just sumcient to raise the cream to pasteurizing temperature, and under atmospheric conditions is introduced at a pressure only slightly in excess of atmos pheric, the cream falling from the orifices 43 in rain or diffused form, being surrounded by the steam which also fills the central space within the chamber 31 due to there being no orifices in the spray ring 42 of Figure 6 or spray plate ii of Figure 7 in this vicinity.

In order to be sufiiciently long in contact with the steam while the cream is in diffused or rain form, the distance of fall from the spray orifices 43 to the bottom of chamber 31 should be a minimum of about three feet, this fall ensuring the raising of temperature of the cream to that of the steam.

Used as atmospheric machines, the cream would have to be pumped or would flow by gravity to the spray ring 42 (Figure 6) or fluid cham ber 49 (Figure 7) and as there would be no necessity for a seal on the inlet pipe 2, a float tank 44 would not be required.

With the pasteurizers of Figures 6 and '7, used in conjunction with a deodorizer apparatus 64, the pasteurizer would have its inlet pipe 2 passing from float tank 44 (Figure 6) and the goose neck pipe 41 connected by pipe II to the deodorizer 64. said deodorizer preferably having the retardation means therein as shown in Figure 5.

Assuming that it is desired to pasteurize at 190 F., as with the pasteurizers of Figures 1 and 2, a vacuum of 11 inches would be required in the pasteurizer chamber 31 and the vacuum to be maintained in the deodorizer 64 would be 11 inches plus that required to raise the weight of cream from the goose neck pipe 41 into the deodorizer 64 via pipe II.

The steam admitted to the pasteurizing chamber 31 under 11 inches of vacuum would fall' containing the condensed steam, together with the uncondensed steam being drawn up by way of the goose neck pipe 41 and pipe ll into the deodorizer.

The goose neck pipe 41 would tend to cause a certain amount of cream to accumulate therein so as to form a seal and thus minimize direct passage of steam from the pasteurizing chamber 37 to the deodorizer 64.

The cream within the deodorizer 54 may be retarded before delivery therefrom by the retarder means such as previously described and illustrated in Figure 5.

I claim:

1. A method of pasteurizing liquids comprising continuously and gently diffusing steam from the exterior into direct contact with all particles of a flowing, substantially thinned body of the liquid in a container to cause a substantially in- 

